Plural component spray guns are used for the spray application of two-component materials such as gel-coats, polyesters and fast setting materials such as foam insulation. Generally, the two components react with one another requiring mixing of these components during application. In this regard, during operation of the spray gun, two or more components are supplied to the spray gun via separate supply sources (e.g., supply lines leading to separate component reservoirs). Often, one or all components are supplied under pressure and/or preheated. Once received by the spray gun, the components are combined in a mixing chamber and expelled under pressure (e.g., fluid pressure and/or air pressure) via a nozzle prior to the components beginning to set.